Question

How many grams of coffee must evaporate from 350 g of coffee in a
100-g glass cup to cool the coffee from 95.0ºC to 45.0ºC ? You may
assume the coffee has the same thermal properties as water and that the
average heat of vaporization is 2340 kJ/kg (560 cal/g). (You may neglect
the change in mass of the coffee as it cools, which will give you an
answer that is slightly larger than correct.)

Answer 1

the sum of the heats gained is zero.

350cwater*(45-95)+100cglass(45-95)+M*2340=0

look up the cwater, and cglass, an solve for M

Answer 2

सिध कीजीये कि गुरुत्व के अधिन मुक्त रुप से गिरते पिंड की बातिक ऊर्जा सदैव निपती रहती है उत्तर